The present invention relates to an absorption cold/hot water generating machine. More particularly, the present invention relates to an absorption cold/hot water generating machine which permits easy sampling of a solution (absorbing solution).
Among absorption cold/hot water generating machines of this type, one having a construction as shown in FIG. 4 is conventionally used. The conventional absorption cold/hot water generating machine comprises, as shown in FIG. 4, an evaporator 1, an absorber 2, a condenser 3, a low-temperature generator 4, a high-temperature generator 5, a solution pump 6, a refrigerant pump 7, a cooling water pump 14, a solution heat exchanger 16, and a cooling tower 17, with piping 9 for connecting these components.
In the absorption cold/hot water generating machine, usually, a refrigerant which is sprayed in the evaporator 1 by means of the refrigerant pump 7 evaporates in the evaporator 1, and takes heat from water sent from a load L by means of a cold/hot water pump 15, thereby producing cold water. Refrigerant vapor produced through evaporation in the evaporator 1 is absorbed, in the absorber 2, by a high-concentration solution fed from the high-temperature generator 5 through the piping 9.sub.1 and 9.sub.2 via the solution heat exchanger 16 and sprayed in the absorber 2 and the concentrated solution thus becomes a lower-concentration diluted solution.
The diluted solution in the absorber 2 is sent to the high-temperature generator 5 though the piping 9.sub.6 and 9.sub.3 via the heat exchanger 16, and to the low-temperature generator 4 through the piping 9.sub.6 and 9.sub.4 via the heat exchanger 16 by the solution pump 6, heated in the high-temperature generator 5 and the low-temperature generator 4, respectively, and sent back to the absorber 2 in the form of the concentrated solution to continue the refrigerating cycle. Cooling water in the cooling tower 17 is circulated by the cooling water pump 14 through the absorber 2, the condenser 3 and the cooling tower 17. The solution pump 6, the refrigerant pump 7, the cooling water pump 14 and the cold/hot water pump 15 are controlled by the controller 10. In FIG. 4, the reference numeral 11 is an inverter for driving the solution pump 6; 18 is a buzzer which sounds upon the occurrence of a problem in the absorption cold/hot water generator; and 19 is a sampling valve for taking out the absorbing solution.
In the high-temperature generator 5, the diluted solution sent from the absorber 2 by the solution pump 6 is heated, and the refrigerant is evaporated to produce the concentrated solution which flows into the header 8. The concentrated solution returns from the header 8 to the absorber 2 through the piping 9.sub.1 and 9.sub.2 and the solution heat exchanger 16. Electrodes 12 and 13 serving as liquid level sensors for detecting the liquid level are provided in the header 8. The electrode 12 is used for detecting a high level, and the electrode 13 is used for a low level.
The inverter 11 controls the operating frequency of the solution pump 6 in response to a command from the controller 10 to control the rotating speed of the solution pump 6, thereby controlling the flow rate of the diluted solution to be fed to the high-temperature generator 5. More specifically, when the solution level in the header 8 is lower than a predetermined minimum value, the inverter controls the solution pump 6 so as to increase the flow rate of dilute solution fed to the high-temperature generator 5. When the solution level in the header 8 is higher than a predetermined maximum value, the inverter controls the solution pump 6 so as to reduce the flow rate of diluted solution fed to the high-temperature generator 5. Thus, the solution level in the header 8 is kept within a certain range.
In order to inspect the operating condition of the absorption cold/hot water generating machine having the above-mentioned construction, it is necessary to detect a concentration of the diluted solution (absorbing solution). More specifically, it is the general practice to open a sampling valve 19 provided on the discharge side of the solution pump 6, take out the diluted solution into a container such as a measuring cylinder, and measure specific gravity and temperature of the diluted solution, thereby calculating the concentration of the diluted solution. It should be noted that, in sampling, the interior pressure of the absorption cold/hot water generating machine is usually lower than the atmospheric pressure.
In an absorption cold/hot water generating machine having the above construction, however, it is not easy to conduct sampling (extraction) of the diluted solution. That is, when an operating frequency of the solution pump 6 is low, the discharge pressure of the solution pump 6 does not exceed the atmospheric pressure. Thus, if the sampling valve 19 is opened in this state, air is immixed into the piping 9, thus causing the machine to become inoperable condition or to corrode. A common practice for solving this problem is to prepare a container such as a sampling tank, reduce the inner pressure of the container to a vacuum, and then open the sampling valve 19 to take a sample of the diluted solution into the container. This method of sampling is, however, problematic in that it consumes a considerable amount of time and labor.
There is also proposed a method of increasing the discharge pressure of the solution pump 6 by forcibly increasing the operating frequency of the solution pump 6 to thereby create a condition for sampling of the diluted solution. In this method, however, it is necessary to dispose a number of operators including one who monitors an overflow in the header 8, one who conducts sampling by operating the sampling valve 19 and one who controls the inverter 11 of the solution pump 6. In addition lack of cooperation among the plurality of operators may cause immixture of air into the piping 9 of the absorption cold/hot water generating machine due to sudden decrease in the operating frequency of the solution pump 6, stoppage of the solution pump 6 or a delay in closing of the sampling valve 19.